Metallurgical process.



JOSEPH E. JOHNSON, JR, or NEW YORK, N. Y.

METALLURGICAL PROCESS.

No Drawing.

To all whom/.62? may concern;

Be it known that I, JOSEPH E. JOHNSON, Jr., a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Metallurgical Processes, of which the following is a specification.

This invention relates to an improved process for recarbonizing and resiliconizing ferrous metals, more particularly such metals as steel, in order to convert it into cast iron, that is iron containing substantially 2% or more of carbon, although the process may be employed to give other ferrous metals not-possessing the same the desired amount of carbon, or of silicon and carbon to convert them into cast iron.

It may be explained that the metallurgical definition of steel is that it is an alloy of iron and carbon containing up to 2% of carbon, and that the metallurgical defini-,

' tion of cast iron is that it is an alloy of iron and carbon containing 2% and upward of carbon. Practically, steels seldom if ever contain more than 1.75% of carbon, and good cast irons seldom contain less than 3.25% of carbon, so that in practice there is a wide interval between the carbon con- The difficulty of introducing carbon by the ordinary known means increases greatly after the carbon content passes 2% which is still well below that necessary to make good cast iron.

The improved process is of peculiar value in the" treatment of steel in the form of steel-scrap, to convert the same into cast "iron, steel-scrap in certain localities being very inexpensive, while in the same localities cast iron is very expensive. The elements which distinguish cast iron from steel, are primarily carbon, silicon and phosphorus, the two first mentioned elements being perhaps themost important.

Some carbon may be introduced into the steel-scrap by mixing carbon in some convenient form with it before, during, or after the melting process, but the amount of carbon that will be absorbed under these conditions, is less than that necessary to make good cast iron. Silicon may be introduced into the metal, as is now customary, in the form of ferro-silicon, but the high cost of ferro-silicon makes its commercial use undesirable for this purpose.

I have found that by employing carbid of Specification of Letters Patent.

Patented June as, tart.

Application filed October 21, 1913. Serial No. 796,430.

silicon, commonly known as carborundum, as a means of incorporating both carbon and silicon in the metal, the two disadvantages above mentioned, insuflicient carbon, and excessive expense for silcon, may be overcome, as carbid of silicon in amorphous form may be obtained at a cost only a little over half that of ferro-silicon, and by. reason of the fact that as the carbid of silicon dissolves in the bath on account of the great avidity of low silicon metal for silicon, the carbon is left in the nascent condition, and in this condition is readily absorbed by the molten bath, even though the latter may be saturated for a carbon in its ordinary condition.

In carrying my invention into efiect in utilizing steel-scrap, I melt down by any suitable and appropriate means, a quantity of steel-scrap so as to produce a molten bath of the same. Into this bath, I introduce and thoroughly mix therewith, a suitable quantity of carbid of silicon, preferably in amorphous form. As the carbid of silicon dissolves in the bath, the silicon will unite with the iron and will leave the carbon in the nascent condition, and in this condition the carbon will readily combine with the steel. The combination of the carbon and silicon with the steel is assisted by the fact that heat is developed by the disassociation of the constituent elements of the silicon carbid. It will be understood that I introduce suflicient carbid of silicon so that the final metal produced shall contain not less than 2% and preferably 3% of carbon, constituting cast iron.

Instead of incorporating all bon necessary, by the method of procedure just described, I may first introduce in the ordinary way into ,the bath of steel, as much carbon as it will readily take up, and then supply the remainder of the carbon necessary, and the necessary amount of silicon, by mixing carbid of silicon with the bath, in the manner described;

If it is desired to add phosphorus also, this can be done by charging the bath with a suitable phosphate, the result being that the silicon in the bath will reduce the phosphate so that it will combine with the metal.

of the car I In this action the amount of silicon will be menace enabled to utilize steel-scrap for the producpractice of my process will result in a great scrap, but is applicable also to saving of expense.

ile I have described specifically my method as applied to utilizing steel-scrap for the production of cast iron, it will be understood that the invention in its broader view is not limited in its application to steelsteel, and other ferrous metals, in the conversion of such into cast iron. For instance, in a certainprocess for oxygenating cast iron, invented by me and forming the subject matter of an application filed on the 13th day of August, 1913, S. N., 784,492 the silicon content is reduced, and also the carbon content may be somewhat reduced, the said process contemplating the' subsequent supply of silicon to the treated metal and also the raising of the carbon content until it reaches the proper point for the ends in view. The present process of recarbonizing and resiliconizing above set forth, may be employed to give to this metal of reduced In testimony whereof I silicon and carbon content, its proper amount of these constituents.

Furthermore, the process may be employed for introducing more carbon into a bath of metal which isalready close to the saturation limit of this material, the use of the process for this purpose being desirable in cases where it is necessary for the metal to be high in carbon. By adding carbid of silicon to metal of this character, that is, where it already is nearly saturated, the carbon will be readily absorbed in proper quantity, without an undesirable increase in term erature.

aving thus described my invention, what I claim is:

The process of converting steel-scrap into cast iron, which consists in melting the steel-scrap to produce a molten bath of the same, and then introducing into said bath a sufficient quantity of carbid of silicon to convert the steel into cast iron.

have affixed my signature in presence of two witnesses.

JOSEPH EJOHNSUN, JR.

- Witnesses:

W. R. KENNEDY, WM. J. DoLAN. 

